NASA Science: At Work in an Endless Frontier

By Edward Goldstein

In January 2015, attendees at the 225th meeting of the American Astronomical Society were among the first to see retro-style travel posters (available for download on the internet) inviting visitors to see the sights of “Kepler-186f, Where the Grass Is Always Redder on the Other Side,” or “Relax on Kepler-16b, The Land of Two Suns Where Your Shadow Always Has Company,” or perhaps to “Experience the Gravity of HD 40307g – A Super Earth.”

These fanciful renderings of alien planets by NASA Jet Propulsion Laboratory visual strategists Joby Harris and David Delgado were based on discoveries by the agency’s Kepler Space Observatory, launched in 2009, of the first validated Earth-sized planet to orbit a distant star in the habitable zone (Kepler-186f), and a planet that, like Tatooine in the movie Star Wars, orbits two stars (Kepler-16b) but would not be suitable for Luke Skywalker because it has a temperature similar to dry ice (-109°F); as well as by groundbased observatories of a planet eight times more massive than Earth where skydiving would be a thrilling endeavor (HD 40307g).

What’s remarkable about the Kepler observatory and its discovery of 2,652 confirmed exoplanets along with a further 2,737 unconfirmed planet candidates as of September 2018, is that until 1992, not a single planet had been found outside our solar system. More broadly, Kepler is representative of a NASA science enterprise that through its Science Mission Directorate has more than fulfilled the expectations of the nation at the time of the agency’s founding, when President Dwight D. Eisenhower observed “a developing space technology can … extend man’s knowledge of the Earth, the solar system, and the universe.”

Thanks to NASA’s science enterprise, in the last 25 years alone, the space agency has made huge strides in advancing astrophysics, planetary exploration, heliophysics, and Earth science. Among NASA’s greatest science hits are:

• The launching, repair, and operations of the Hubble Space Telescope well beyond its planned operating life, leading to fundamental discoveries about the size and age of the universe, the existence of supermassive black holes at the centers of galaxies, the galactic environments in which quasars reside, and the processes by which stars form.

• The Cosmic Background Explorer Satellite (COBE), whose work in validating the Big Bang theory of the universe earned NASA senior astrophysicist and project scientist John Mather the 2006 Nobel Prize for Physics, which he shared with George F. Smoot.

• The operations on Mars of the Sojourner (1997), Spirit (2003-2010), Opportunity (2003-present), and Curiosity (2011-present) exploration rovers, which have helped characterize the red planet’s geography and document evidence of water in Mars’ ancient history.

• The orbiting of Saturn by the NASA-European Space Agency and Italian Space Agency Cassini spacecraft (2004-2017), leading to the discovery of three new moons (Methone, Pallene, and Polydeuces) and observations of water ice geysers erupting from the south pole of the icy moon Enceladus, and the placement of the Huygens probe on the surface of Saturn’s moon Titan (2005).

• The placement at the Earth-sun Lagrangian (L1) point of the NASA- European Space Agency Solar and Heliospheric Observatory (SOHO) mission (1995), a mission that demonstrated we could detect and provide early warning of coronal mass ejections, which can harm power grids and other infrastructure, and the launching of the twin STEREO spacecraft (2006), which allowed scientists to witness the solar wind in 3-D for the very first time.

• The operations of the Earth Observing System, a series of satellites that provide long-term global observations of our land surface, biosphere, the solid Earth, atmosphere, and oceans, thus giving scientists much of the data they need to characterize and understand the interaction of these natural systems on Earth.

What sets NASA’s Science Mission Directorate apart today from the earliest incarnations of scientific pursuits at the agency are the significant opportunities that recent scientific, technological, and social advances have enabled.

For example, following on its scientific successes with robotic missions to the planets and with its orbiting observatories, NASA has the compelling overarching mission to search for evidence of extraterrestrial biological life in places like Mars, the subsurface oceans of Europa, or in the atmospheres of Earth-like planets orbiting other stars’ habitable zones. The 2021 launch of the NASA-European Space Agency-Canadian Space Agency James Webb Space Telescope to the second Lagrange (L2) point 1.5 million kilometers from Earth will put in place the successor to Hubble; it can peer farther into the universe as well as more effectively look for biosignatures of liquid water and atmospheric gases such as oxygen that might indicate the presence of life. The Mars 2020 Rover, which will select a collection of rock and soil samples that could be returned to Earth on a future mission, will also further our search for life in the universe.

New technological capabilities associated with human spaceflight, such as the heavy-lift Space Launch System slated for its first flight in late 2019 (though 2020 is more likely), could serve the functions of launching larger space telescopes and facilitating the Europa Clipper mission, which will send a robotic spacecraft to fly by Jupiter’s moon Europa. And once we do mount a Europa mission, said David Lavery, NASA program executive for solar system exploration, in 2014, “The further out applications that you are going to see will be much more radical in terms of their operations, capabilities, and autonomy when we start to look at having what is essentially a robotic submarine that’s going to have to be able to go through the ice cap on Europa all the way down to the liquid ocean underneath, and be able to self deploy and actually have autonomous navigation under the ice cap and transmit all the data back. To operate in an environment that we’ve never seen before and only have a hint of what it’s going to be like is going to be a huge step forward in terms of robotic capability.”

Related to the relatively recent social phenomenon of crowd-sourcing, NASA has invited citizen-scientists to help astronomers discover embryonic planetary systems hidden in infrared data from the Wide-field Infrared Survey Explorer, launched in 2009. “I think citizen science is tremendous,” said Geoffrey Yoder, Deputy Associate Administrator of the NASA Science Mission Directorate. “We’re using taxpayer money for everything that we’re doing, and to be able to have gains from citizen science is just phenomenal.”

Growing linkages between the human spaceflight world and NASA’s scientific undertakings, as illustrated by the Space Launch System, are another positive development. These links have helped bridge the historic divide between factions supporting either human space activity, or robotic exploration, but not both.

On the International Space Station (ISS), science has been given a big lift from the development of commercial cargo capabilities that have enabled more experiments to be sent to the orbiting research laboratory. Increasing demand for research time on the facility has resulted in the adjustment of schedules in the last few years to allow for more hours allocated for science. Further bolstering the utility of the designated U.S. National Laboratory onboard the ISS is the fact that ISS operations have been extended until at least 2024.

The range of ISS experimentation is quite broad. In human health studies, for example, the ISS added a new capability for medical and pharmaceutical research using lab animals in 2014. Astronaut Scott Kelly’s one-year stay onboard the ISS, which ended in March 2016, enabled medical researchers to examine how his body responded to extended exposure to microgravity as compared to his identical twin brother, Mark, who remained on Earth. Kelly’s extended stay also helped the agency prepare for the significant medical and psychological challenges of sending crews to Mars. Earth Science has seen the completion of the successful Cloud-Aerosol Transport System (CATS) investigation, which ran from January 2015 to October 2017, and used a light detection and ranging (LiDAR) system to investigate clouds and aerosols for climate research. In Astrophysics, the Cosmic Ray Energetics and Mass (CREAM) instrument was sent to the ISS in 2017, officially becoming “ISS-CREAM,” where it measures – without interference from Earth’s atmosphere – the energy of cosmic rays and their effect on the composition of the universe, and the Neutron star Interior Composition Explorer (NICER) is studying the exotic states of matter inside neutron stars, where density and pressure are higher than in atomic nuclei. “I spent five years at the Johnson Space Center and I’m seeing science on the ISS that I never thought I’d see,” said Yoder in 2014. “It’s great to see that marriage happening. The same goes for humans to Mars. We’re laying the foundation for human spaceflight to Mars. It’s just a tremendous opportunity if we work as a team.”

NASA’s stated science vision is, in part, to use “the vantage point of space to achieve with the science community and our partners a deep scientific understanding of our planet, other planets and solar system bodies, the interplanetary environment, the Sun and its effects on the solar system, and the universe beyond. In so doing, we lay the intellectual foundation for the robotic and human expeditions of the future while meeting today’s needs for scientific information to address national concerns, such as climate change and space weather.” The Science Mission Directorate’s work is organized into four divisions: Heliophysics, Earth Science, Planetary Science, and Astrophysics.

NASA’s Heliophysics Division studies the sun in many wavelengths in order to better understand why it is so dynamic and how its constant radiation affects the space around it, Earth, and all the planets. Such information can enable detection and prediction of extreme conditions in space that will help to protect life and society and to safeguard human and robotic explorers beyond Earth. Some current and near-future Heliophysics missions include:

• Magnetospheric Multiscale (MMS), an undertaking with partners in Japan and Europe, launched four spacecraft in 2015 to study the mystery of how magnetic fields around Earth connect and disconnect, which is helping us understand magnetic reconnection in the atmosphere of the sun and other stars, in the vicinity of black holes and neutron stars, and at the boundary between our solar system’s heliosphere and interstellar space.

• The Parker Solar Probe was launched on Aug. 12, 2018, on a mission to travel into the sun’s atmosphere – flying closer to the sun’s surface than any previous spacecraft – to understand how the sun’s corona is heated and how the solar wind is accelerated.

• The Global-scale Observations of the Limb and Disk (GOLD) mission features an imaging instrument flying aboard a commercial communications satellite in geostationary orbit to image the Earth’s thermosphere and ionosphere. The satellite carrying the GOLD instrument launched in January 2018, and science operations will commence later this year.

• The Ionospheric Connection Explorer (ICON) satellite, with a planned October 2018 launch, will explore the boundary between Earth and space to understand the physical environment between our world and our space environment.

• Solar Orbiter Collaboration, a joint NASA/European Space Agency mission with launch currently foreseen in 2020, will orbit the sun and study it from a close-up distance of 26 million miles every five months to help improve understanding of how the sun determines the environment of the inner solar system.

NASA’s Earth Science Division aims to develop a scientific understanding of Earth as an integrated system of diverse components (its atmosphere, lithosphere, hydrosphere, cryosphere, and biosphere) and that system’s response to natural or human-induced changes, and to improve prediction of climate, weather, and natural hazards.

Some key Earth Science missions are:

• Soil Moisture Active/Passive (SMAP), a probe to map the moisture content of the Earth’s soil every three days has been helping scientists to better understand weather and hydrological cycle processes since it launched in January 2015.

• Ice, Cloud, and land Elevation Satellite-2 (ICESat-2), which launched on Sept. 15, 2018, will measure changes in ice sheet height, a key indicator of climate change.

• The Planetary Science Division explores and observes objects in the solar system to understand how they formed and how they have evolved, which can shed light on Earth’s development as a life-sustaining body. This in turn can help inform exploration and finding locations elsewhere in the universe where life could have existed or could exist today.

• The division’s New Horizons mission is helping researchers understand worlds at the edge of the solar system. With its 6-month flyby study of Pluto in 2015 (with closest approach on July 14 of that year), New Horizons completed NASA’s close-up reconnaissance of – International Astronomical Union be damned – the nine solar system planets. Since then, the mission has ventured deeper into the Kuiper Belt and soon will conduct – on Jan. 1, 2019 – a flyby of the small Kuiper Belt object 2014 MU69 (nicknamed Ultima Thule). The encounter with Ultima Thule, which orbits a billion miles beyond Pluto, will mark the farthest ever exploration of any planetary body.

As the New Horizons mission makes its way to its next flyby target, the Dawn spacecraft’s mission exploring Ceres and Vesta, the two most massive objects in the asteroid belt, is drawing to a close – once its supply of hydrazine, a key fuel, runs out in September-October 2018, communication with Earth will cease. But in the time it has been in operation (the spacecraft was launched in 2007, spent 14 months in Vesta’s orbit starting in 2011, and began transmitting data from Ceres in 2015), Dawn has returned valuable information that gives researchers insight on the origins of the solar system: the number of craters in Vesta’s northern hemisphere revealed during mapping suggests that the planet-like object experienced more large impacts and that there were more large objects in the asteroid belt earlier on than scientists thought, and the chemistry of an ancient ocean was found on the surface of Ceres – data analysis suggests there may still be liquid under the surface.

Elsewhere in the solar system, the Cassini spacecraft embarked on the final phase of its mission to Saturn, during which the spacecraft performed nearly two dozen daring loops around the planet, passing through the gap between Saturn and its innermost ring, before plunging into the planet’s atmosphere (to protect moons that could have conditions suitable for life) on Sept. 15, 2017. The agency also placed the Juno spacecraft in orbit around Jupiter in July 2016 to investigate the planet’s atmosphere, including possible water content, and to advance understanding of the planet’s origin and evolution. In May 2018, NASA launched InSight, a robotic Mars lander equipped with a seismometer and heat flow probe to study Mars’ early geological evolution. It will land on the Martian surface in November 2018.

The Planetary Sciences Division also performs planetary defense work, which entails finding and tracking near-Earth objects (NEOs) that pose a hazard of impact with Earth; characterizing those objects to determine their orbit trajectory, size, shape, mass, composition, rotational dynamics and other parameters, so that experts can determine the severity of the potential impact event, warn of its timing and potential effects, and determine the means to mitigate the impact; and planning and implementation of measures to deflect or disrupt an object on an impact course with Earth, or to mitigate the effects of an impact that cannot be prevented. Mitigation measures that can be taken on Earth to protect lives and property include evacuation of the impact area and movement of critical infrastructure.

Missions that address this planetary defense effort include the retasking of the Wide-field Infrared Survey Explorer (WISE) astrophysics spacecraft, now labeled NEOWISE, to look for NEOs, and the launch in 2016 of OSIRIS-REx, a mission to robotically approach and return a sample from Bennu, a carbonaceous asteroid, the most common variety of asteroid. The spacecraft is scheduled to return to Earth with the sample in 2023. DART, or Double Asteroid Redirection Test, is a mission planned to demonstrate an asteroid deflection technique for planetary defense. According to Lindley Johnson, planetary defense officer at NASA headquarters, “DART would be NASA’s first mission to demonstrate what’s known as the kinetic impactor technique – striking [an] asteroid to shift its orbit – to defend against a potential future asteroid impact.”

Finally, the Astrophysics Division studies the universe to understand how it works, how it began, and how it evolved, and searches for life on planets around other stars. On April 18, 2018, the Transiting Exoplanet Survey Satellite (TESS) launched from Cape Canaveral, beginning a two-year mission to detect small planets with bright host stars in the solar neighborhood. TESS will monitor the brightnesses of more than 200,000 stars, searching for telltale temporary drops in brightness caused by planetary transits. The mid-2020s will see the launch of the Wide Field Infrared Survey Telescope (WFIRST), a NASA observatory designed to investigate dark energy, exoplanets, and infrared astrophysics. With its 2.4-meter primary mirror, Wide Field instrument, and coronagraph, TESS will be able to survey large areas of the sky to measure the effects of dark matter and energy on the shape and distribution of galaxies in the universe, survey the inner Milky Way to find approximately 2,600 exoplanets, and conduct high-contrast imaging and spectroscopy of dozens of nearby exoplanets.

NASA marks the 28th anniversary of the Hubble Space Telescope launch this year, even as it readies the James Webb Space Telescope to succeed Hubble. Scheduled to launch in 2021, Webb will study every phase in the history of our universe, from the first luminous glows after the Big Bang, to the formation of solar systems capable of supporting life on planets like Earth, to the evolution of our own solar system. The telescope will be the premier observatory of the next decade, and will provide a wealth of information to thousands of astronomers.

“Today, NASA is leading efforts to answer a host of important questions for humanity,” said Dr. Thomas Zurbuchen in 2016, when he was named head of NASA’s Science Mission Directorate, “Where do we come from? How did life originate? How are Earth’s environments changing? There has never been a more pivotal time to solve these mysteries.”